The present invention relates generally to spark plugs and methods of producing the spark plugs.
A spark plug for internal combustion engine usually has a center electrode and another ground electrode, which upon supplying of an electrical potential generate a spark for igniting fuel in an internal combustion engine. Since the ignition is performed many thousand times due to an electrical discharge at the electrodes, the electrodes are subjected to erosion which reduces their service life. In order to increase the service life, it was proposed to apply reinforcing materials on the facing surfaces of the electrodes by the range of different techniques. Some techniques require sophisticated equipment and control, following shaping electrode tips into final configuration (attaching by welding small reinforce metal pieces to electrode ends, inserting metal wire in a hole of central electrode tip, plasma welding technique, etc.). Other processes apply a layer of reinforcing material by sputtering or coating methods which can not provide reliable bonding between the electrode substrate and the layer material at high temperature spark plug operating conditions and could result in failure of a spark plug. Most of techniques use precious metals as a reinforcing material, which have extremely high cost. Some spark plugs of the above mentioned general type are disclosed in U.S. Pat. Nos. 3,673,452, 4,810,220, 4,881,913, 5,179,313, 5,456,624; 5,779,842; etc.